Merge AudioRendererImpl and AudioRendererBase; add NullAudioSink

content/renderer/media/renderer_webaudiodevice_impl.h

Index: content/renderer/media/renderer_webaudiodevice_impl.h
diff --git a/content/renderer/media/renderer_webaudiodevice_impl.h b/content/renderer/media/renderer_webaudiodevice_impl.h
index a70c08848e94d8d1f2da8347c5176fbbdf119f71..5b06242e4a6a197d002a8361f32eedf397278ebb 100644
--- a/content/renderer/media/renderer_webaudiodevice_impl.h
+++ b/content/renderer/media/renderer_webaudiodevice_impl.h
@@ -30,9 +30,9 @@ class RendererWebAudioDeviceImpl
   virtual double sampleRate();
 
   // AudioDevice::RenderCallback implementation.
-  virtual size_t Render(const std::vector<float*>& audio_data,
-                        size_t number_of_frames,
-                        size_t audio_delay_milliseconds) OVERRIDE;
+  virtual int Render(const std::vector<float*>& audio_data,
+                     int number_of_frames,
+                     int audio_delay_milliseconds) OVERRIDE;
   virtual void OnRenderError() OVERRIDE;
 
  private: